This disclosure is directed generally to an integrated drive generator for use with an aircraft gas turbine engine, and more specifically, to an oil pump assembly of an integrated drive generator.
Integrated drive generators have been in use for many years in generating electrical power on airframes. An integrated drive generator functions to produce a constant three-phase 400 Hz alternating current when driven by a variable speed gearbox located on an airframe propulsion engine, generally a gas turbine engine. The integrated drive generator is a single unit that includes a hydraulic speed trimming device and an alternating current generator mounted within a case assembly. The hydraulic speed trimming device converts a variable speed shaft input from a gearbox on a gas turbine engine to a constant speed shaft output to drive the alternating current generator.
The integrated drive generator also generally includes a scavenge pump, an inversion pump, and a charge pump disposed within the case assembly of the integrated drive generator. The scavenge pump draws oil from an oil sump located in the bottom of the case and supplies the oil to a filter which removes various debris within the oil prior to entering the cooling circuit located external to the integrated drive generator on the aircraft. The output of the deaerator, which contains oil of higher quality than that pumped by the scavenge pump, is applied to the intake of the charge pump. The charge pump pressurizes the oil and applies the oil to an oil circuit. The oil circuit supplies oil to the hydraulic speed trimming device, to the alternating current generator for cooling and lubricating the alternating current generator, to the casing of the integrated drive generator for cooling, and to other components of the integrated drive generator that require oil circulation for cooling and/or lubrication. Generally, an assembly of gears is used to mechanically connect the scavenge pump, the inversion pump, and charge pump to the output of the hydraulic speed trimming device.
Should any part of the integrated drive generator require maintenance or replacement, an operator generally must open the case assembly and at least partially disassemble the integrated drive generator. Reducing the complexity of the integrated drive generator results in maintenance cost savings by reducing the amount of parts to maintain within the integrated drive generator and the amount of time required to disassemble and reassemble the integrated drive generator. Reducing the complexity of the integrated drive generator also results in manufacturing cost savings by reducing the number of parts needed to produce the integrated drive generator and the time required to assemble the integrated drive generator.